The present invention relates to synthetic surfacing systems, including such systems that may be used for athletic playing surfaces.
Traditionally, a number of natural and artificial surfaces have been used to create athletic playing surfaces such as basketball and tennis courts, soccer and football fields, and track and field venues. Frequently, artificial surfaces, such as the Astroturf brand of synthetic turf systems, are used inside domed stadiums and arenas instead of natural playing surfaces. Artificial surfaces may also be constructed for outdoor tracks, basketball courts and tennis courts in order to obtain particular surface characteristics (such as those relating to bounce or rebound) or in an attempt to eliminate the cost of maintaining a natural surface. In all such circumstances, it is desirable to achieve particular surface characteristics, depending on the nature of the use intended, while minimizing the cost of construction and maintenance.
While there are many varieties of athletic playing surfaces, all can be generally categorized as one of two types: (1) those which are intended to provide a hard-surfaced playing area; and (2) those which are designed to simulate a natural grass playing area. All of these surfaces are generally comprised of multiple layers of materials which are laid upon one another in some fashion.
Regardless of the type of system, the life of an artificial surfacing system may be determined by a number of factors, including the integrity of the system construction, the durability of the components of the system, the condition of the base upon which the system is placed, climate and weather conditions encountered by the system, the amount and nature of play on the surface and the passage of time.
Those surfacing systems which are designed to provide a substantially hard playing surface, such as tracks, basketball courts and tennis courts, are generally comprised of crushed rock or other similar material, asphalt or concrete pavements, or a multi-layer system that is built on top of a crushed rock or pavement base. Such systems are subject to the development of cracks or other forms of degradation of the playing surface as a result of weather and climate effects, improper construction, improper maintenance, normal or excessive use or wear, or simply the passage of time. In most cases, the cracking or degradation results in diminished playing characteristics such as xe2x80x9cdead spotsxe2x80x9d or areas of the playing surface which do not possess the same qualities or characteristics as the remainder of the surface. Frequently, the owner of a cracked or degraded surface will elect to patch the playing surface in an attempt to avoid the expense of a complete resurfacing. While a patch may provide a temporary reprieve from further cracking and degradation, in most cases the patch is more susceptible to an accelerated failure than the original surface. Furthermore, it is likely that the patch will have different qualities and characteristics from the remainder of the playing surface. In order to restore the original quality and surface characteristics of the original system, it may be necessary to overlay the degraded or cracked surface with a new layer of the surfacing material. However, if the source of the failure is the underlying pavement or base material, it may be necessary to completely remove and reconstruct the entire playing surface system.
Artificial systems that are designed to provide a hard-surfaced playing area are generally rigid and unyielding, and consequently, they tend to impose higher levels of stress and strain on the joints of the user, unless the systems include layers of flexible materials such as urethane or acrylic encapsulated rubber. However, a disadvantage of such systems with flexible layers is that these layers tend to bubble and delaminate over time as moisture penetrates between the layers of the system or is transmitted through the underlying base pavement by way of hydrostatic pressure.
Artificial surfacing systems which are designed to simulate a grass playing surface generally incorporate a number of different layers including an asphalt, crushed rock or concrete base and a surface layer of tufted or woven pile fabric. Sometimes such systems include one or more intermediate layers. One such system, as described in U.S. Pat. No. 3,801,421 of Allen et al., includes an asphalt substrate, an intermediate layer of particulate vulcanized rubber bonded with polyisocyanurate resin, and a top layer of pile fabric including tufts of nylon, polypropylene or polyester that are designed to simulate natural grass. Another system of this type is described in U.S. Pat. No. 3,740,303 of Alderson et al., which includes a mat having an upper pile layer of nylon fibers tufted through a backing material. The upper pile layer is uniformly adhered to the upper surface of a non-woven batt by an adhesive and the batt is adhered to an underlying asphalt layer by an adhesive or to an underlying sand layer by a soil stabilizer. The height of the pile may be varied to best accommodate the intended use of the surface.
Other artificial playing surfaces of this type have incorporated in-fill materials which are placed on and into the upstanding pile tufts in order to create a playing surface which provides cushioning, resiliency, and a more natural turf feeling. For example, U.S. Pat. No. 3,995,079 of Haas describes a synthetic turf-like product comprising a pile fabric which includes a flexible backing and a plurality of generally upstanding pile elements. The pile elements are generally woven or knitted into the backing and are configured to resemble grass. A quantity of non-compacting, irregular shaped granular material, such as granulated coal slag, crushed granite and/or flint, is interspersed among the pile elements and on the backing of the pile fabric to a depth sufficient to substantially absorb the shock of objects impacting thereon.
Although the surfacing systems which employ woven or tufted fabrics and an in-fill material may simulate the feel and other characteristics of natural turf, such systems frequently require maintenance to prevent the in-fill material from dispersing or concentrating in one or more areas, thereby leaving other areas of the playing surface with inadequate support or unacceptable playing characteristics. Consequently, some such systems also employ binders to bond a portion of the in-fill material to the tufts so that such portion remains in position relative to the tufts and so that no shallow or unprotected areas develop in the bound portion of the in-fill layer. U.S. Pat. No. 4,396,653 of Tomarin describes a playing field surface formed of a synthetic fiber carpet, having generally upright pile fibers, upon which one or more layers of particulate covering is applied. The carpet, which is laid upon a support base of gravel or sand, includes woven base sheet, the lower side of which is coated with a rubber-type coating. Tufted through the base sheet are a plurality of fiber tufts having a length of one-half to two and one-half inches. The fibers are densely tufted so as to form a tightly packed, intertwined network. A first layer of rubber-like particles is applied to a predetermined depth to form a lower layer. A binder, such as a rubber adhesive or cement, may be sprayed or spilled upon the lower layer so as to trickle down between and connect the rubber particles. An upper layer, formed of sand-like particles, is then placed atop the lower layer. In most instances, the upper layer of particulate will be applied so that at least the tips of the fibers remain exposed. The sand-like upper layer and the exposed fibers combine to simulate a natural grass field and tend to reduce compaction of the fiber tufts. Of course, this upper layer is still subject to shifting and dispersing, and consequently, would still require periodic maintenance to retain consistent performance characteristics.
Although known surfacing systems are suitable for use either as a simulated grass surface or as a hard surface, none of the known systems are adaptable for either type of use. It would be desirable, therefore, if a surfacing system could be developed which is adaptable to various types of use, including use as a driveway or parking area surface. It would be also desirable if a monolithic surfacing system could be developed that may be installed on a variety of compacted base materials without requiring the removal, grading or planing thereof, and which would not show, transmit or be affected by defects or cracks in the base materials. It would also be desirable if a surfacing system could be developed that offered the advantages of systems containing in-fill materials but without the post-installation maintenance typical of such surfacing.
The present invention provides a surfacing system containing a-pile fabric, an in-fill material, a wear coating, and a binder that are bound together in monolithic structure. Such a surfacing system can be applied over an existing pavement or other base, which may or may not have existing defects such as cracks, in such a manner that such defects in the base will not usually affect the surface characteristics or quality of the newly installed surfacing system. Another advantage of the invention is that the surfacing system may be applied to a non-level base material in such manner that the resulting surface is substantially planar and monolithic.
Another advantage of the present invention is that it provides a surface which exhibits good shock absorption characteristics for an athlete, while providing the necessary attributes which ensure the proper feel (i.e. roll and bounce or rebound) of a ball which may be used thereon. It is another advantage of the present invention that the same system can be used to produce a variety of surfaces having different characteristics, for both athletic and non-athletic end uses, by varying the length of the pile elements, the amount or type of in-fill material, the amount or type of binder, and the amount or type of the wear coating or finish.
It is another advantage of the invention to provide a surfacing system which is more durable than standard asphalt or concrete finishes and which can be used for virtually continuous play for long periods of time without exhibiting unacceptable wear. Another advantage of the invention is that its various components and layers are contained in a monolithic structure which is not susceptible to moisture intrusion, and consequently is not susceptible to bubbling or delamination of any of its components. It is yet another advantage of the invention that it may be economically repaired or rejuvenated in the event that it is damaged.
It is another advantage of the invention that the pile fibers employed in the surfacing system are neither exposed to the elements nor exposed in the playing surface, so that they do not need to exhibit the same appearance qualities (i.e. ultraviolet stabilization, depth of color and colorfastness) as pile fibers used in other systems, thereby allowing for a reduction in the production cost of the surfacing system.
Other advantages and features of the present invention will become apparent to those skilled in the art to which the invention relates from an examination of the drawings and ensuing description.
As used herein, the term athletic surface or playing surface refers to any surface, such as a grass field, asphalt or concrete surface, synthetic surface, basketball court, tennis court or the like, upon which an athletic activity may take place.
As used herein, the term artificial surfacing system or surfacing system refers to any playing surface or other artificial surface that is constructed of various components. Such systems typically are comprised of a plurality of sequentially-placed layers or components that may or may not be bound together.
As used herein, the term base refers to a surface or layer upon which the surfacing system is applied or constructed.
As used herein, the term binder refers to material which may be added between or among the various components of an artificial surfacing system so as to bind the components of the system, or at least some of them, together.
As used herein, the terms pile elements, pile fibers and tufts refer to fibers and filaments that may be woven, knitted or tufted into a backing.
As used herein, the terms in-fill, in-fill material and filler refer to the materials or combination of materials which are interspersed between and amongst the pile elements of the surfacing system.
The surfacing system of the present invention comprises a monolithic system having a top layer and a bottom layer. The bottom layer includes a pile fabric having a flexible backing and a plurality of upstanding pile elements, each of which has an upper and a lower end. The system also includes a quantity of in-fill material which is sufficient to form a layer of substantially uniform density extending from the flexible backing of the bottom layer to substantially the upper end of the pile elements when it is interspersed amongst the pile elements. The top layer comprises a wear coating or layer having an upper and a lower surface, and the system includes a binder which binds the bottom layer, the in-fill layer and the top layer together to create a monolithic structure.
The invention also includes a method of forming the surfacing system disclosed herein. According to this method, a pile fabric is provided. This fabric has a flexible backing and a plurality of generally upstanding pile elements, each of which has an upper end and a lower end. A quantity of in-fill material is applied amongst the generally upstanding pile elements to form a layer of in-fill material of substantially uniform density extending from the flexible backing of the pile fabric to substantially the upper ends of the pile elements. A binder is then applied to the pile fabric and in-fill material and a wear coating or finish coating is applied to the top of the layer of in-fill material so that at least some of the upper ends of the pile elements penetrate and are bound to the lower surface of the wear coating.
Stated somewhat more specifically, a preferred embodiment of the present invention includes a polypropylene pile fabric which is tufted to a flexible backing. A non-skid, moisture-resistant coating is then applied to the bottom of the backing. A quantity of in-fill material, having a particle size that is less than 30 U.S. Screen mesh and which comprises sand, lava, rock, particles of cork or ceramic material, or a combination thereof, is uniformly interspersed amongst the polypropylene pile elements until the in-fill material forms a layer of substantially uniform density which extends from the flexible polypropylene backing to the upper ends of the pile elements. A binder is applied to the pile fabric and in-fill material. A wear coating, preferably an acrylic latex material, is applied to the top of the layer of in-fill material so that at least some of the upper ends of the pile elements contact and are bound to the lower surface of the wear coating, wherein the pile elements reinforce the system and anchor the top layer of the system to the bottom layer of the system. The binder acts to bind all of the system components together so as to create a monolithic surfacing system for use as a playing surface, walkway, driveway, parking area or the like.
In order to facilitate an understanding of the invention, preferred embodiments of the invention are illustrated in the drawings, and a detailed description thereof follows. It is not intended, however, that the invention be limited to the particular embodiments described. Various modifications and alternative embodiments such as would ordinarily occur to one skilled in the art to which the invention relates are also contemplated and included within the scope of the invention described and claimed herein.